Control system for automotive automatic transmission

ABSTRACT

An automatic transmission mechanism for an automotive vehicle in which the transmission governing factors such as the position of the speed selecting lever, position of the accelerator pedal and the throttle valve, engine speed, vehicle speed and road grade are measured by electric means and the signals thus obtained are continuously fed into an electronic control system for evaluation of the requirements from the transmission. The electronic control system sends signals to elements converting them into hydraulic pressure which actuates friction elements to change gear ratios of the transmission.

D United States Patent [151 3,640,] 56

Mori et al. 1 Feb. 8, 1972 [54} CONTROL SYSTEM FOR AUTOMOTIVE 3,l22,9403/ I964 Shimwell et al ..74/866 AUTOMATIC TRANSMISSION .762 8/l9663,448,640 6/1969 Nelson ..74/866 [72] Inventors: Yolchi Morl; lllroshlsalchimura, both of Yokohama, Japan Primary Examiner--Arthur T. McKeon[73] Assignee: Nissan Motor Company, Llmlted, Att0mey.l0hn LezdeyYokohama Japan [22] Filed: Oct. 29, I969 [57] ABSTRACT 21] Appl. No.:872,253

An automatic transmission mechanism for an automotive vehicle in whichthe transmission governing factors such as the [30] Foreign ApplicationPrmrny Dan position of the speed selecting lever, position of theaccelera- Oct. 30, I968 Japan ..43/78830 tor Pedal and the throttle l gn p i l peed and road grade are measured by electric means and thesignals {52] us. CL "74,866 74/73 74/752 thus obtained are continuouslyled into an electronic control 74/844 system for evaluation of therequirements from the transmission. The electronic control system sendssignals to elements 2; "860k ;2; g;Z g% ;g* converting them intohydraulic pressure which actuates fn'c- 1 I 0 c tion elements to changegear ratios of the transmission.

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1. An automatic transmission for an automotive vehicle comprising atleast one planetary gear set including actuable friction elementsselectively hydraulically for obtaining different speed ratios;hydraulic means supplying hydraulic pressure to said friction elementsfor actuation of said friction elements; sensing means for sensingvehicle speed, engine speed, position of a speed selecting lever,position of an acceleration control member, and engine torque; andelectrical means responsive to said sensing means and controlling theoperation of said hydraulic means for firstly causing a change of gearreduction ratio to take place at a level of vehicle speed which ishigher the greater the displacement of the acceleration control memberis and for secondly causing variation in the level of the hydraulicpressure in dependence on the engine torque and in dependence on thevehicle and engine speeds.
 2. An automatic transmission of the planetarygear set type according to claim 1, wherein said sensing means includesvacuum level sensing means for sensing vacuum level in an intakemanifold of an engine of the vehicle as a function of the engine torque.3. An automatic transmission of the planetary gear set type according toclaim 1, further comprising inclination-sensing means for sensing thelongitudinal inclination of said vehicle, wherein said electrical meansis responsive to said inclination-sensing means for raising the level ofvehicle speed at which the change of gear reduction ratio is caused totake place both when the vehicle is ascending and when the vehicle isdescending.
 4. An automatic transmission of the planetary gear set typeaccording to claim 1, further comprising temperature-sensing means forsensing engine temperature, wherein said electrical means is responsiveto said temperature means for raising the level of vehicle speed atwhich the change of gear ratio is caused to take place when enginetemperature is low.
 5. An automatic transmission of the planetary gearset type according to claim 1, further comprising brake-sensing meansfor sensing brake operation of said vehicle, wherein said electricalmeans is responsive to said brake-sensing means for raising the level ofvehicle speed at which shifting down is caused to take place when thebrake operation is effected.
 6. An automatic transmission of theplanetary gear set type according to claim 1, comprising a torqueconverter, wherein said sensing means comprises first voltage-generatingmeans for generating voltage proportional to the rotational speed of theoutput shaft of said engine, second voltage-generating means forgenerating voltage proportional to the rotational speed of the drivenshaft of said vehicle, third voltage-generating means for generatingvoltage proportional to an angular position of the throttle valve of thecarburetor of said engine, wherein said electrical means comprises anelectrical circuit including an emergency switch, a starter switch, amanual lever operated selector switch selectively connectable to saidemergency switch and to said starter switch, and electronic calculatingmeans connected for reception of the voltage from first and secondvoltage-generating means and electric signals from said selector switchthrough said emergency switch for comparing the relative values of saidreceived voltages and electrical signals and upon detecting apredetermined gear shift point, for developing a selective signal toinitiate a gear shift for supplying a signal to a throttle valvecontroller independently of the position of said accelerator pedal,synchronizing the speed of sAid engine output shaft with the speed ofsaid driven shaft, for developing a timer signal to cause a momentarypressure fall in said hydraulic pressure while said gear shift takesplace, and for developing a signal for causing a selected engagement anddisengagement of at least one of said friction members to effect saidgear shift; and wherein said hydraulic means comprises a regulatorvalve, a hydroelectronic converting means connected for reception ofsaid timer signal and for the speed of a turbine shaft of said torqueconverter for supplying a hydraulic signal to said regulator valve;electromechanical valve means responsive to said hydraulic pressure forcausing actuation of at least one of said friction members, and solenoidvalve means connected for reception of said timer signal for controllingthe level of said hydraulic pressure while said gear shift takes place.7. An automatic transmission of the planetary gear set type according toclaim 6, wherein said electrical means comprises a low speed limit relayconnected to said electronic calculating means and said throttle valvecontroller for resetting the position of said throttle valve when theengine speed is lower than a predetermined level.
 8. An automatictransmission of the planetary gear set type according to claim 7,wherein at least one manually controllable low forward speed powertrain, at least two electronically controllable forward speed powertrains and at least one manually controllable reverse power train areprovided.
 9. An automatic transmission of the planetary gear set typeaccording to claim 8, wherein said emergency switch, when in emergencyposition, provides electrically a high forward speed power train whilelow and intermediate forward speed and reverse power trains arehydraulically provided.
 10. An automatic transmission of the planetarygear set type according to claim 8, wherein said electronic calculatingmeans develops a signal for changing the input/output ratio into a highforward speed power train when said vehicle is decelerated to a completehalt and the throttle valve is closed and a signal for changing saidinput/output ratio into a low forward speed power train when saidthrottle valve is opened by depressing said accelerator pedal, therebyavoiding vehicle creep during said halt but providing a high torquepower train for easily starting said vehicle from said halt.
 11. Anautomatic transmission of the planetary gear set type according to claim8, wherein said friction elements comprises a second clutch having itsdrive portion connected to a turbine shaft of said torque converter anda driven portion, and a first brake; and wherein said planetary gear setcomprises a first planetary gear set including a first ring gearconnected with said driven portion of said second clutch, a first sungear and a plurality of first planet gears all of which are rotatablyconnected with a first carrier connected with said driven shaft and arealso meshed with both said ring and sun gears, a second planetary gearset including a second sun gear integrally and axially connected withthe sun gear of the first planetary gear set, a second ring gearconnected with said driven shaft and a plurality of second planet gearsall of which are connected with a second carrier and meshed with saidsecond ring and sun gears, whereby a power train for a low speed ratiois provided for forward drive through the drive portion of said secondclutch when the driven portion thereof is engaged with the drive portionthereof, the first ring gear of the first planetary gear set engagingwith the drive portion of said second clutch connected with said turbineshaft, said first planet gears engaging with said first ring gear, saiddriven shaft being connected with said first planet gears through thefirst carrier connected therewith and said first brake providing areaction element.